Free ID CDL Double/Triple Trailers Practice Test 2025

If you’re an Idaho resident and want to drive combination vehicles with two or even three trailers or semi-trailers, you’re in luck. Idaho is a double- and triple-friendly state. Double pup trailers are legal nationwide, ID included. However, Idaho also allows the following types of Long Combination Vehicles on some of its major roads: Rocky Mountain Doubles (a standard-size trailer followed by a pup trailer), Turnpike Doubles (two full-length trailers), B-Trains (two full-length semi-trailers), and even Triples (three pup trailers). LCV drivers are in high demand because few drivers have the necessary endorsements or training to operate such vehicles.

If you want to drive LCVs, start by obtaining a Class A CDL (including passing the General Knowledge and Combination knowledge tests). Obtaining the Air Brakes qualification is a practical necessity. For this qualification, you must pass the Air Brakes knowledge test and a skills test in a Class A combination vehicle with air brakes. Then pass the Double/Triple knowledge test to obtain a Double/Triple (T) endorsement on your Class A CDL. (Note that no special skills test is required for this endorsement.)

Idaho also requires you to undergo specialized training to operate LCVs. Once completed, you’ll receive an LCV Driver Training Certificate.

The official Double/Triple knowledge test covers such topics as safe handling, air brakes on doubles and triples, coupling and uncoupling, rollovers, and trailer sway. This knowledge test is based on the official Idaho CDL manual (Idaho CDL Handbook 2025), especially Chapter 7: Doubles and Triples. You likely studied other chapters of this manual to get your CDL and perhaps obtain some other endorsements too. But before you go back to the manual once again, this time to study for the Double/Triple endorsement, we would like to offer you a smarter approach. It supplements the manual to ensure you’ll pass the Double/Triple knowledge test on your first try.

This Idaho Doubles and Triples Endorsement Practice Test is based on the official CDL manual, just like the official Double/Triple knowledge test. It’s up to date as of October 2025. The 20 multiple-choice practice questions and answers on this practice test address such topics as air lines, converter dollies, coupling, following distance, rearward amplification, and rollovers.

If you need help answering a practice question, ask our AI Assistant to give you a hint or rephrase the question. You can also ask your own questions. If you still miss the question, the AI Assistant will immediately give you the correct answer and an accompanying explanation. Disappointed with your final score? You can retake this practice test as often as you wish.